塑钢纤维轻骨料混凝土与钢筋粘结锚固试验研究

通过对内贴应变片钢筋的直接拔出试验，分析钢筋直径、相对锚固长度（l_a/d）及混凝土相对保护层厚度（c/d）对塑钢纤维轻骨料混凝土与钢筋间粘结性能的影响，得出不同钢筋直径、锚固长度及相对保护层厚度对试件粘结锚固性能的影响规律，并提出塑钢纤维轻骨料混凝土钢筋锚固长度计算公式。试验结果表明：随钢筋直径的增大，试件粘结刚度增强，极限粘结强度先提高后降低；增加钢筋锚固长度会降低试件极限平均粘结强度，同时极限粘结强度对应钢筋自由端滑移量减小，试件粘结韧性则随锚固长度的增加而减小；混凝土相对保护层厚度增加会使试件极限粘结强度先提高然后趋于平稳。根据试验结果得到的钢筋锚固长度计算公式与规范给出的计算公式进行比较，从极限粘结强度的角度看，规范中的钢筋锚固长度计算公式偏于保守。

RESEARCH ON BOND-ANCHORAGE BEHAVIOR BETWEEN DEFORMED BARS AND HPP FIBER REINFORCED LIGHTWEIGHT AGGREGATE CONCRETE

Through pull-out test of steel bars with strain gauges attached inside, the effect of bar diameter, l_a/d and c/d on the bond performance between steel bars and HPP fiber reinforced lightweight aggregate concrete was analyzed. The results of the pull-out test with different influential parameters showed that the bond stiffness between the bar and concrete was enhanced with the increase of steel bar diameter, and the ultimate bond strength was increased firstly and then decreased as the diameter was increased. The ultimate bond strength and corresponding free end displacement was reduced as the anchorage length was increased. The bond toughness declined as l_a/d was increased. The ultimate bond strength was increased firstly and then tended to become stable with the increase of the relative thickness of concrete cover. By comparing the bar anchorage length formula according to the test results with that given in the code, it was shown that the bar anchorage length formula in the code is conservative in terms of ultimate bond strength.